LONG-TERM INTRAOCULAR TOXIC EFFECTS OF TOPICAL MITOMYCIN-C IN RABBITS

Purpose: To detect whether toxic intraocular effects of mitomycin C (M MC) after extraocular application are long-standing or are reversible over time. Methods: We placed sponges soaked with MMC on the intact sc lera of rabbit eyes after incision of the conjunctiva. Controls receiv ed sponges soaked with balanced salt solution. Concentrations of MMC w ere 0.1 and 0.2 mg/ml. The eyes were examined histologically after 6 a nd 12 months. Results: In all MMC-treated eyes, pathologic changes of the ciliary epithelium were present, which included irregular cell sur faces, intracytoplasmatic vacuoles, swelling of mitochondria, and diso rganization of the endoplasmic reticulum. Nerves within the ciliary bo dy also exhibited mild-to-moderate loss of axons in nonmyelinated nerv es and increase of interstitial collagen deposition. Capillaries withi n the ciliary body consistently had a thickened basement membrane, whi ch was arranged in two to three layers in multiple areas. The changes seen were similar in eyes examined at 6 and 12 months after applicatio n of MMC. Conclusions: These results suggest that toxic intraocular ch anges are dose dependent and do not recover over time. The impact of t hese findings on humans is unclear, but may further emphasize the high toxic potential of MMC.